Raman Spectroelectrochemistry for Batteries: Real-Time Insights into Electrochemical Processes

Batteries are essential for modern energy storage because of their safety and high energy density. To meet the growing global energy demand, significant improvement of existing electrode materials and the development of new ones are required. Achieving this goal demands a deep understanding of electrochemical reactions, degradation pathways, and thermal behavior under realistic operating conditions. Raman spectroscopy, including in situ, operando, and ex-situ techniques, has emerged as a powerful, nondestructive tool for probing these mechanisms at the molecular level. It enables the detection of changes in the molecular structure and composition of electrodes, solid electrolytes, and their interfaces, thereby providing critical insights for enhancing battery performance. This review comprehensively examines the application of Raman spectroelectrochemistry in monitoring structural and chemical transformations during battery operation, such as ion intercalation, electrolyte decomposition, and interfacial reactions. By correlating Raman signatures with key degradation processes, including capacity fading, structural deterioration, and mechanically induced failure, this review underscores the technique's unique role in diagnosing performance limitations and guiding the rational design of durable and efficient energy-storage systems. Finally, current challenges such as methodological standardization, spectral sensitivity, and spatial resolution are discussed, highlighting future directions for operando battery analytics and sustainable energy technologies.